Fix some arc/mercurial issues

Summary:
  - In "arc which", we recommend "--rev x --rev ." to show changes. This is not accurate if there are uncommitted changes in the working copy. Just "--rev x" shows the correct changes (implicitly, the other end of the range is the working copy state).
  - When you diff only working copy changes, we currently incorrectly identify all your open revisions as belonging to the working copy. Instead, correctly identify none of them as belonging to the working copy (in theory, we could go farther than this and do path-based identification like SVN, but with --amend in hg 2.2+ this workflow should be going away in the long run).
  - If you have uncommitted working copy changes, never try to amend.

Test Plan: Ran "arc which .", "arc diff ." in a working copy with dirty changes, got better results than before.

Reviewers: dschleimer, btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1507

Differential Revision: https://secure.phabricator.com/D2980
Dump problematic parser patches to temp files in "arc diff"

Summary: I'm trying to get a repro for a Windows + SVN patch issue. Dump patches which fail to a temp file so there's less bewilderment in getting the right patch handed over for analysis.

Test Plan: Forced a parse failure, ran "arc diff", inspected temp file.

Reviewers: btrahan, vrana

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D2997
Fix arc handling of "\n" files on Windows in SVN

Summary:
On Windows, a diff may have "\n" newlines (from the file itself) but "\r\n" blocks (from svn).

NOTE: indents are funky since I edited this with Notepad++, I'll fix before landing.

Test Plan: Diffed an edit to a "\n" newline file on Windows in SVN.

Reviewers: btrahan, vrana

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D2998
Speedup `arc branch`

Summary:
This reduces time of `arc branch` from 13s to 7s in my repo which is faster than `git branch --verbose` (10s).

The price for this speedup is that we loose the information [ahead 1, behind 21242] but we showed it only in branches with no revision so it's not a big deal.

Test Plan:
  $ arc branch

Reviewers: epriestley

Reviewed By: epriestley

CC: ahupp, aran, Korvin

Differential Revision: https://secure.phabricator.com/D3005
Specify error message for some pyflakes messages
Merge pull request #43 from rafikk/master

Specify error severity for some PyFlakes messages
Allow running phpunit tests from any directory

Test Plan: Run `arc unit` anywhere.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D3017
Adding confirmation message to 'arc todo' with information about the task created

Summary: 'arc todo' now logs a message with the task title and URI when run.

Test Plan: Run 'arc todo test' and see that it logs a message with the form 'Created task <task number>: '<task title' at <task URI>

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3016
Merge pull request #44 from ifraimow/master

Adding confirmation message to 'arc todo' with information about the task created
Show "Fnnn" number in "arc upload"

Summary: We don't show the "Fnnn" number, but should.

Test Plan:
```$ arc upload README --conduit-uri=http://local.aphront.com:8080/
Uploading 'README'...
  F121 README: http://local.aphront.com:8080/file/data/fnu76irnwftin4akjpxv/PHID-FILE-yrjeblelwq6rv5a5gjko/README

Done.```

Reviewers: phleet, btrahan, vrana

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D3023
Fix ambiguous argument where a branch has the same name as a file

Summary: Currently, if you have a branch named "docs" and a local file named "docs", `git show -s docs` complains because it's ambiguous. Use `--` to unambiguously mark branches as revisions, not files.

Test Plan: Ran `arc branch` in a working copy with a "docs" branch and a "docs" file, got expected results.

Reviewers: vrana, btrahan

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D3030
Enable raising lint warnings for mulitple lines at once

Summary:
We have a lint rule checking if some string is too long.
This string can span multiple lines.
If we report a warning at the first line then it is muted if the first line wasn't modified.
We need to say that this whole block is wrong and report it when at least one line from the block was modified.

Test Plan: Changed a lint rule to call `raiseLintAtLines()` and verified that the warning is reported even if the changed line isn't first.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3029
Create a mysterious new workflow

Summary:
Phabricator, as we all know, is marketed as a fun adventure game. However, while it is occasionally fun and often an adventure, it's so far been sorely deficient in the game aspect. This patch aims to rectify that oversight. (Presence of the first two qualities is not guaranteed.)

Note: In case there's any doubt, this is not a serious suggestion. I was bored.

Test Plan: Seriously?

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3026
Fix parsing of "hg diff -r x:y" diffs

Summary: When you run `hg diff -r x:y`, we get two "-r" arguments in the diff header. Currently, we parse this incorrectly.

Test Plan: Added unit test which previously failed; test now passes.

Reviewers: dschleimer, btrahan

Reviewed By: dschleimer

CC: aran, cakoose

Maniphest Tasks: T1550

Differential Revision: https://secure.phabricator.com/D3061
Enrich arc configuration and add stronger typing

Summary:
See <https://github.com/facebook/arcanist/issues/45>

Currently, when the user types `arc set-config x false`, we set it as the string "false", which is usually not desirable. We have some steps toward typed config already, but expand on what we have and move as much stuff as possible into it, including all the config settings that aren't currently documented (there are still some lint-specific and project-specific settings not present here, but this is most of it).

Also make the `phutil_libraries` key a legacy name for `load`, and `immutable_history` a legacy name for `history.immutable`. Generally the goal here is to make config simpler and bring it more in-line with Git/Mercurial, which use dotted hierarchies.

I'll add some documentation here but I think most of the changes should be fairly straightforward.

Test Plan:
  - `arc set-config history.immutable on` (And similar -- sets to boolean true.)
  - `arc set-config history.immutable off` (And similar -- sets to boolean false.)
  - `arc set-config history.immutable derp` (And similar -- raises exception.)
  - `arc set-config history.immutable ''` (And similar -- removes setting value.)
  - `arc set-config --show`
  - `arc get-config`
  - `arc get-config base`

Reviewers: dschleimer, bos, btrahan, vrana

Reviewed By: dschleimer

CC: aran

Maniphest Tasks: T1546

Differential Revision: https://secure.phabricator.com/D3045
Allow hyphens in arc library names

Summary:
We've had these in our library names and they're quite useful as word
separators. Allowing them shouldn't cause any trouble.

Test Plan:
ran arc liberate in an empty directory, and it didn't complain when I gave
it a name with a hyphen.

Reviewers: epriestley, vrana, jungejason

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3070
Minor, improve behavior of arc get-config.
Added support for 'hg export' diff format

Summary: This diff format is used by de-facto mercurial GUI called "TortoiseHG".
It is available as the only way to copy diff into clipboard (right click commit,
select "export", select "copy patch". I added this format support into arcanist
so revisions in Differential can be created from TortoiseHG via simple copy-
paste. Unit test added, manually tested.

See: https://github.com/facebook/arcanist/pull/46

Reviewed by: epriestley
Include extension classes in the builtin list

Summary: Just like we ship with a list of extension functions, add a list of extension classes so people stop getting lint errors about DOMDocument just because some linter uses it.

Test Plan: Ran "arc lint".

Reviewers: vrana, btrahan, codeblock

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D3082
Make arc patch show the superior error message if you are not authenticated

Summary: ...by making requireAuthentication return true if conduit is required.

Test Plan: mv ~/.arcrc ~/.arcrcbak; arc patch D12121; <verify error message>

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1522

Differential Revision: https://secure.phabricator.com/D3014